Some non-volatile memory devices, such as Flash devices, comprise arrays of memory cells. Data retention refers to the ability of the memory cells to retain reliable reading of the stored data for long periods of time. Methods for achieving data retention in non-volatile memories are known in the art.
For example, U.S. Pat. No. 8,432,733, whose disclosure is incorporated herein by reference, describes techniques for compensating in a non-volatile storage for differences in floating gate coupling effect that are experienced by non-volatile storage elements belonging to different word lines. A set of the non-volatile storage elements are assigned for storing data, and at least one of the non-volatile storage elements, which is a neighbor to one of the data non-volatile storage elements, is assigned as a dummy element that does not store data. After programming the data non-volatile storage elements, a programming voltage is applied to the dummy element so as to create a coupling compensation effect to the neighbor data non-volatile storage element.
U.S. Pat. No. 8,593,884, whose disclosure is incorporated herein by reference, describes a method for data retention. The method includes sampling a plurality of nonvolatile memory devices, which are included in a data storage device, in order to detect retention information for each of the nonvolatile memory devices, and outputting result data derived from the retention information to a host. The host conditionally performs a respective retention operation on each of the nonvolatile memory devices based on the result data.